Electric railway signal system.



1.1. RUDDICK.

ELECTRIC RAILWAY SIGNAL SYSTEM.

APPLICATION FILED 'JAN.3. 19H.

1,1 5 1,720. Patented Aug. 31, 1915.

COLUMBIA PLANOGRAPH 60., WASHINGTON, D. c.

rin'rrnn s rarns ra rnn r orato JOHN J'. RUDDICK, OE NEWTON,MASSACHUSETTS, ASSIGNOR TO UNITED STATES ELECTRIC SIGNAL COMPANY, OFWEST NEWTON, MASSACHUSETTS, A CORPORA- TION OF MASSACHUSETTS.

ELECTRIC RAILWAY SIGNAL SYSTEM.

Specification of Letters Patent.

Patented Aug. 31, 1915.

To all whom it may concern Be it known that I, JOHN J. RUDDIOK, acitizen of the United States, residing at Newton county of Middlesex,and State of Massachusetts, have invented an Improvement in ElectricRailway Signal Systems, of which the following description, inconnection with the accompanying drawing, is a specification, likecharacters on the drawing representing like parts.

This invention relates to electric railway block signal systems andespecially to that type of signal system wherein the signalsetting andsignal-restoring circuits are connected to insulated sections of therails and are closed to operate the signal by the pas sage of a car oversuch insulated sections. One advantage of signal systems of this type isthat the signal-setting and signalrestoring circuits can be completedwithout the use of trolley switches or other devices connected with thetrolley wire and operated by the trolley wheel; but when sig nal systemsof this type are so arranged that the signal-setting andsignal-restoring circuits carry the full voltage of the trolley wire ormain conductor, it is practically impossible to so insulate theinsulated track sections from the remainder of the track as to preventan appreciable leakage of the current through the insulation, and as aresult there is a continuous loss of current and the system is renderedunreliable because the current leakage may be sufficient to cause thesignal to be operated without the presence of a car on the insulatedsection.

The principal object of my invention is to provide a novel block signalsystem of the above-mentioned type wherein the circuits which areconnected to the insulated track sections carry current of acomparatively small voltage, thus making it possible to so insulate theinsulated track sections as to prevent any detrimental leakage ofcurrent. v

Other objects of my invention will be more fully hereinafter describedand the novel features of the invention will then be pointed out in theappended claim.

In the drawing I have shown diagrammatically a sufficient portion of ablock signalsystem to illustrate the operation of my invention.

My invention is adapted for use inconnection with almost any type ofelectrically operated block signal and therefore I have not deemed itnecessary to illustrate herein any particular signal in detail.

I have shown at 3 a signal box which may contain the usual signal orsignals indicating danger or safety, which signals may be operated byany appropriate mechanism, not shown. It is customary to place thesignal box at the end of the block whether the latter is a section ofone of the tracks of a double-track railway, or a section of asingle-track railway.

For the sake of illustrating the invention, I have herein shown aportion of a block comprising a section 4 of a single track which has atone end a turn-out 5 to permit the cars to pass. The current foroperating or restoring the signal in the box 8 is taken from the mainconductor or trolley wire 6 through a circuit 7 which connects with asignal setting circuit 10 and a signal-restorin r circuit 11, both ofwhich lead to the signa box.' Each of said circuits has therein a switchof some suitable construction by which it is open or closed. The switchin the signal-setting circuit 10 is shown as comprising the two contacts9 and 12 adapted to be closed by the switch blade 13. The switch in thesignal-restoring circuit 11 is shown as comprising two contacts 8 and14L that are adapted to be connected by the switch blade 15. When thebranch circuit 10 is closed, the current from the trolley wire 6 willpass into the signal box 3 and set the signal, while when the circuit 11is closed, the current passing into the signal box will restore thesignal to its normal position.

Inasmuch as the invention does not relate to the particular form ofsignal in the signal box, I have not deemed it necessary to furtherillustrate the device.

The switch blade 13 is operated to close the signal-setting circuit 10by means of a signal-setting magnet 20, and the switch blade 15 isoperated to close the signal-restoring circuit 11 by means of asignal-restoring magnet 22. These signal-setting and signal-restoringmagnets are controlled by the current in two signal-initiating circuits19 and 21, the circuit 19 being connected to an insulated rail section17 in one rail 16 of the turn-out 5, and the circuit 21 being connectedto an insulated rail section 18 in the rail 30, and in the embodiment ofthe invention shown this control is secured by placing the coils of thesignal-setting and signal-restoring magnets '20 and 22 1n the circuits19 and 21 respectively. The insulated rail section 17 is shown asconnected by a wire with an insulated section 32 in the rail 30, and theinsulated rail section 18 is connected by a wire 41 with the insulatedrail section 31 in the rail 16.

The switch blade 13 is shown as pivotally hung to a suitable support at25 and has associated therewith an armature 26 which is attracted by themagnet 20 when the latter is energized. Similarly, the switch blade 15is shown as pivotally mounted at 27 and as having associated therewiththe armature 28 for the magnet 22. l/Vhen either of the magnets 20 or 22are energized, therefore, the corresponding switch blades are swung intoposition to close one or the other of the branch circuits 10 or 11.

l/Vhen a car in traveling in the direction of the arrow at on the branchtrack 5 reaches the insulated track section 17, said section 17 will beconnected electrically with the rail 29 of the track 5 through the cartrucks, and thus the circuit 19 controlling the mag net 20 will beclosed, thus energizing the magnet and closing the signal-settingcircuit 10. Similarly, when a car in traveling in the direction of thearrow 6 on the main track reaches the insulated track section 18,

, said track section will be electrically connected through the truckwith the rail 39, thus closing the circuit 21 through the magnet 22 andcausing the switch blade 15 to be operated to close the circuit 11,-thus restoring the signal to its normal or safety position.

Since the signal setting and signal restoring mechanisms are set inoperation by the closing of the circuits 19 and 21, I have herein chosento designate said circuits as initiating circuits. If thesesignal-initiating circuits are connected to the main conductor in such away as to receive the full voltage therefrom, (in electric railwaysystems the main conductor usually carries a current of about 500volts,) the voltage in said circuits will be so great that it will bepractically impossible to insulate the track sections 17, 18, 31 and 32sufliciently to prevent the leakage of current through the insulation,and when there is such a leakage of current the signal system is apt tobe une reliable in its operation. 'It is,-therefore, a desideratum thatthe circuits which are connected to the insulated track sections shouldcarry a comparatively small voltage; in fact, experiments which I havemade have demonstrated that the'best results can be secured by using acurrent of only one or two volts in the circuits which connect with theinsulated rail sections. In order to get this low voltage current in thecircuits it has been proposed to supply them with current from abattery, but this method has many objections.

Hy invention aims to provide a construction whereby this low voltagecurrent in the circuits 19 and 21 can be supplied from the trolley wire6, thus obviating the use of batteries or other auxiliarycurrent-producing devices. In order to secure this end, I connect thetrolley wire 6 with the return rails of the track by a circuit 14 whichhas therein a high resistance 24 of say several thousand ohms, and thenI connect the circuits 19 and 21 by a wire 23 with the circuit 14 on thereturn side of the resistance, as at 45. I find when the connections aremade in this way, that while the shunt circuit 44; will have a highvoltage since it is connected to the trolley wire 6, yet the circuits 19and 21 which are in the nature of shunt circuits between the circuit 44and the tracks will carry a. current of comparatively small voltage, infact of only one or two volts, this being due to the fact that thedifference in potential between the point 15 and the return iscomparatively small. This arrangement, therefore, provides low voltagecircuits 19,21 which are connected to the insulated rail sections, butwhich take their current from the high voltage circuit.

By this arrangement the amount of current which flows in thesignal-initiating circuits 19, 21 is also comparatively small, althoughsufficient to operate the magnets 20 and 22. The use of the low voltagein the circuits 19, 21 makes it perfectly feasible to completelyinsulate the rail sections from the return and thus prevent any leakageof current in the signal-initiating circuits.

The switch 13 has rigid therewith an arm 34: and the switch 15 has rigidtherewith an arm 35. The purpose of these arms is to make the switchnon-interfering.

WV hen the car travels in the direction of the arrow a and comes ontothe insulated track section 17, the magnet 20 will be energized as abovedescribed, thus closing the circuit 10, and as the car passes onto theinsulated track section 31, the magnet 22 will be energized and the arm35 will be swung down onto the arm 34, thus holding the switch 13 closeduntil the car has passed off from both insulated sections. Similarly, ifa car is traveling in the direction of the arrow 6 and the circuit 21 isclosed by the passage of the car"onto the insulated section 18 therebyenergizing the magnet 22 and then subsequently passes onto the insulatedtrack section 32, the closing of the circuit 19 will swing the arm 34down onto the arm 35 and will thus hold the switch 15 in engagement withthe contacts 8 and 14 while preventing the switch 13 from closing thecircuit'lO.

I prefer to use a small resistance 99 of say four or five ohms in thecircuit 44 between the point 4L5 and the rail as better results aresecured thereby.

Having fully described my invention, what I claim as new and desire tosecure by Letters Patent is In a block signal system, the combinationwith a main conductor carrying a Working current, of a trackconstituting the return and provided with an insulated rail section, anormally-open signal-actuating circuit connected to the main conductor,a circuit taking current from the main conductor and connected with thereturn, a potential reducing resistance in said latter circuit whichgives a potential drop in said circuit sufficient so that the potentialon the return side of the resistance is only slightly greater than thatof the return, a signal-initiating circuit connected at one end to theinsulated rail section and at the other end to the second-named circuiton the return side of said resistance, a magnet in said latter circuit,and a switch for the normally-open signal-actuating circuit controlledby said magnet.

In testimony whereof, I have signed my name to this specification, inthe presence of two subscribing witnesses.

JOHN J. RUDDICK.

Witnesses:

JULIA P. GLAzIER, ALFRED E. THAYER.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, I). G.

